Having had this discussion 're the lack of proper training for police officers in the US with someone who has trained police in a number of democratic countries, yes, it's true that all police forces have issues.
Systemic racism, sexism, homophobia etc at varying levels of severity and frequency are just some of the issues police forces worldwide have indeed been grappling with for decades, to differing levels of success.
However, police forces in the US have a self-inflicted problem very few other countries share and that is the lack of training, the lack of education, the low calibre of candidates, the extreme decentralisation of the police forces and their chronic, severe underfunding.
Much of the training time also has to be spent on drumming into the police candidates that suspects have both human rights and civil rights. (Neither a joke nor an overstatement.)
There are almost 18,000 different police forces at city, state and federal level. They all have different rules, different entry and training requirements, different funding, different uniforms and equipment.
These factors combined mean there are huge differences in the quality of police officers across the US. They also mean that there is an overabundance of personalities unsuited to law enforcement work. That's what happens without central oversight holding everyone accountable to the exact same standards.
And no, the latter does not solve, avoid or prevent all problems but it reduces them to a minimum. And yes, even in the US, the majority of police officers are decent, law abiding citizens who seek to do their jobs properly and without treating suspects like the family in that video was treated.
But once you add in the fact that any simple traffic stop, any knock on a door, anything at all can get a police officer shot without provocation, even the decent ones have too much to deal with sometimes.
So, these incidents will keep on happening because they are not individual, isolated failures of an otherwise well designed system, but the natural byproduct of a more than usually flawed one.